Foam sheet and molded product

Abstract

A foam sheet includes a polylactic acid resin composition that includes a polylactic acid resin. The polylactic acid resin includes 98% mol % or greater of D-lactic acid or L-lactic acid that is a constituent monomer unit of the polylactic acid resin. An amount of the polylactic acid resin is 98% by mass or greater relative to a total amount of organic matter of the foam sheet. The foam sheet has a bulk density of 0.063 g/cm3 or greater and 0.250 g/cm3 or less. A surface roughness Sq (root mean square height of the surface) of the foam sheet defined by ISO 25178 is 7 μm or less.

What is claimed is: 
     
         1 . A foam sheet, comprising:
 a polylactic acid resin composition that includes a polylactic acid resin,
 the polylactic acid resin including 98% mol % or greater of D-lactic acid or L-lactic acid that is a constituent monomer unit of the polylactic acid resin, an amount of the polylactic acid resin being 98% by mass or greater relative to a total amount of organic matter of the foam sheet, 
   wherein the foam sheet has a bulk density of 0.063 g/cm 3  or greater and 0.250 g/cm 3  or less, and   a surface roughness Sq (root mean square height of the surface) of the foam sheet defined by ISO 25178 is 7 μm or less.   
     
     
         2 . The foam sheet according to  claim 1 , wherein the foam sheet has the bulk density of 0.063 g/cm 3  or greater and 0.125 g/cm 3  or less. 
     
     
         3 . The foam sheet according to  claim 1 , wherein the surface roughness Sq of the foam sheet is 6 μm or less. 
     
     
         4 . The foam sheet according to  claim 1 , wherein surface roughness Svk (reduced dale height) of the foam sheet defined by ISO 25178 is 8 μm or less. 
     
     
         5 . The foam sheet according to  claim 1 , further comprising:
 a chain extender.   
     
     
         6 . The foam sheet according to  claim 5 , wherein the chain extender includes an epoxy functional chain extender. 
     
     
         7 . The foam sheet according to  claim 1 , further comprising:
 inorganic particles.   
     
     
         8 . The foam sheet according to  claim 1 , wherein the foam sheet includes pores generated by foaming the polylactic acid resin composition with a blowing agent that is carbon dioxide. 
     
     
         9 . The foam sheet according to  claim 1 , wherein the foam sheet has cold crystallization enthalpy of 20 J/g or greater. 
     
     
         10 . A molded product comprising:
 the foam sheet according to  claim 1  having a shape achieved by thermoforming.   
     
     
         11 . The molded product according to  claim 10 , wherein the molded product is a bag, a package, a container, a dish, a cutlery, a buffer material, or a packing material.